#include "stdio.h"
#include <stdlib.h>
#define MaxVertexNum 100
typedef enum{FALSE,TRUE}Boolean;/*FALSE為0,TRUE為1*/
Boolean visited[MaxVertexNum];
int dfn[MaxVertexNum],low[MaxVertexNum],num;
typedef int VertexType;
typedef struct node{/*邊表結點*/
	int adjvex; /*鄰接點域*/
	struct node *next; /*鏈域*/
	/*若要表示邊上的權,則應增加一個數據域*/
}EdgeNode;
typedef struct vnode{ /*頂點表結點*/
	VertexType vertex; /*頂點域*/
	EdgeNode *firstedge;/*邊表頭指針*/
}VertexNode;
typedef VertexNode AdjList[MaxVertexNum];/*AdjList是鄰接表類型*/
typedef struct ALGraph{
	AdjList adjlist;/*鄰接表*/
	int n,e; /*圖中當前頂點數和邊數 */
}Graphic; /*對于簡單的應用,無須定義此類型,可直接使用AdjList類型。*/
Graphic * graph;
void CreateGraphic(Graphic *G)
{/*建立無向圖的鄰接表表示*/
     	int i,j,k;
      	EdgeNode *s;
      	scanf("%d%d",&G->n,&G->e); /*讀人頂點數和邊數*/
      	for(i=0;i<G->n;i++){/*建立頂點表*/
        	G->adjlist[i].vertex=getchar(); /*讀入頂點信息*/
        	G->adjlist[i].firstedge=NULL;/*邊表置為空表*/
       	}
      	for(k=0;k<G->e;k++){/*建立邊表*/
         	scanf("%d%d",&i,&j);/*讀入邊(vi,vj)的頂點對序號*/
         	s=(EdgeNode *)malloc(sizeof(EdgeNode)); /*生成邊表結點*/
         	s->adjvex=j; /*鄰接點序號為j*/
         	s->next=G->adjlist[i].firstedge;
 	        G->adjlist[i].firstedge=s; /*將新結點*s插入頂點vi的邊表頭部*/
         	s=(EdgeNode *)malloc(sizeof(EdgeNode));
         	s->adjvex=i; /*鄰接點序號為i*/
         	s->next=G->adjlist[j].firstedge;
         	G->adjlist[j].firstedge=s; /*將新結點*s插入頂點vj的邊表頭部*/
        }   
} 
void DFS(Graphic *G,int i)
{ /*以vi為出發點對鄰接表表示的圖G進行深度優先搜索*/
    EdgeNode *p;
    printf("visit vertex：%c",G->adjlist[i].vertex);/*訪問頂點vi*/
    visited[i]=TRUE; /*標記vi已訪問*/
    p=G->adjlist[i].firstedge; /*取vi邊表的頭指針*/
    while(p)
		{/*依次搜索vi的鄰接點vj,這里j=p->adjvex*/
      	if (!visited[p->adjvex])/*若vi尚未被訪問*/
        	DFS(G,p->adjvex);/*則以Vj為出發點向縱深搜索*/
      	p=p->next; //找vi的下一鄰接點
     }
}
void dfnlow(int u,int v)
{/*采用dfs遍歷，計算dfn和low compute ，u表示起始結點,v 是u的父親結點*/
        VertexNode ptr;
        int w;
        dfn[u] = low[u] = num++;
        for (ptr =graph->adjlist[u]; ptr; ptr= ptr->next ) 
		{
             w = ptr->vertex;
             if (dfn [w] < 0) {
				dfnlow (w,u);
                low[u] = _min(low[u], low[w]);
             }
             else if ( w != v)
                low [u] = _min( low[u], def[w]);
        }
}
void init (void)
{
        int  i;
        for ( i = 0; i <MaxVertexNum; i++ ){
           visited [i] = FALSE;
           dfn[i] = low[i] = -1;
        }
        num = 0;
}
void bicon( int  u, int  v)             
{/*計算dfn和low，以及輸出G的重連通分量*/ 
    	node_pointer ptr;
        int w,x,y;
        dfn[u] = low[u] = num++;
        for (ptr =graph->adjlist[u]; ptr; ptr= ptr->nex){
             w = ptr->vertex;
             if(v!= w && dfn[w] < dfn[u])
                add (&top, u, w);                           
             if ( dfn [ w ] < 0) {        
                    bicon(w,u);
                    low[u] = _min(low[u],low[w]);
                    if (low[w] >= dfn[u]{
                      printf ("New biconnected component:");
                      do { /* delete edge from stack */
                         delete (&top, &x, &y);
                         printf (" <&d,&d>",x,y);
                      } while ( !((x == u) && ( y == w)));
                      printf ("\n");
                }     
             }  
             else if (w != v)  low[u] = _min(low[u], dfn[w]);
         }   
}
void main(void)
{
	CreateGraphic(graph);
	init();
	dfnlow(1,4);
	bicon(1,4)
}